The human knee joint is subject to greater stress than any joint in the body. This is because it must bear the full weight of the body, often at disadvantageous leverage ratios. Consequently, there is a premium on the design of a prosthesis for replacement of the knee joint.
Additionally, the implantation of a prosthesis should avoid resection of any more of the joint than is strictly necessary. This is especially true of the knee which includes ligaments within the joint, i.e., the cruciate ligaments which are important for the future functioning of the joint, and, therefore, in the design of the prosthesis it is important to keep the thickness of the prosthesis to a minimum so as to avoid resection, but yet to do so without sacrificing consistent and long term adequate performance.
Other factors to be considered in the design of a knee prosthesis include the need to anchor it against the forces of shear, tipping, and torque to which the knee joint is particularly susceptible.
Furthermore, it is desirable to standardize the manner in which the prosthesis is implanted and to provide instrumentation by which the tibial plateau and femur are resected in such a way as to make the excisions fit with the components to be applied to the plateau.
An improved modular total knee prosthesis which meets the challenge of restoring a natural, individual knee motion pattern and derived from substantial clinical experience, detailed anthopometric data and state-of-the-art computer graphic stimulations is described and claimed in copending applications U.S. Ser. No. 52033 and U.S. Ser. No. 97286.
U.S. Application Ser. No. 52033 provides a tibial component and application Serial No. 97286 provides, in combination, a femoral component and tibial plateau. The disclosures in both these applications are incorporated herein by reference.
The present invention is concerned with improved instrumentation to facilitate implantation of a total knee prosthesis such as disclosed in (but not limited to) the aforementioned applications.